Centrifugal separator for fibrous material

ABSTRACT

A centrifugal separator with a circular inner chamber and an outer chamber of decreasing cross section from a relatively large tangential inlet to a relatively small tangential outlet. The two chambers communicate through a semicircular arrangement of individually adjustable blades forming a portion of the boundary between the chambers extending between the tangential inlet and outlet.

United States Patent Mark [ 1 June 27, 1972 [54] CENTRIFUGAL SEPARATOR FOR FIBROUS MATERIAL [72] Inventor: Andre Mark, 54, Cours Lafayette, 69,

Lyon, Rhone, France [22] Filed: May 15, 1969 [21] Appl.N0.: 824,949

[30] Foreign Application Priority Data May 15, 1968 France ..68500l9 [51] Int. Cl. ..B04c 1/00 [58] Field of Search ..209/143, 144, 210, 211; 55/DIG. 37

[56] References Cited UNITED STATES PATENTS 3,001,727 9/1961 Block et a1. ..209/144 X 2,039,692 5/1936 Van Tongeren ..209/144 UX 1,897,195 2/1933 Howden ..209/144 1,914,282 6/1933 OToo1e.... ..209/144 2,087,789 7/1937 Allardice ..55/DIG. 37 3,091,334 5/1963 Morton ..209/210 X FOREIGN PATENTS OR APPLICATIONS 1,003,016 2/1957 Germany ..209/144 Primary Examiner-Frank W. Lutter Assistant Examiner-Ralph J. Hill Att0rneySughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT A centrifugal separator with a circular inner chamber and an outer chamber of decreasing cross section from a relatively large tangential inlet to a relatively small tangential outlet. The two chambers communicate through a semicircular arrangement of individually adjustable blades forming a portion of the boundary between the chambers extending between the tangential inlet and outlet.

2 Claims, 9 Drawing Figures CENTRIFUGAL SEPARATOR FOR FIBROUS MATERIAL It is known that wooden fiber-boards are manufactured by first of all making a mattress of one or several layers of fibers impregnated with a polymerizable resin and, thereafter, compressing this mattress under heat so as to polymerize the resin. By this method very stiff objects with good mechanical properties can be obtained. In common practice the mattress is made by having an air current carry the fibers onto a carpet of wire gauze, i.e. a forming wire. This carpet is arranged to glide over the perforated upper surface of a suction box.

In order to get surfaces of a pleasing aspect, mostly three layers are utilized, namely two exterior layers made of fine fibers and one intermediate layer consisting of coarser fibers. The prior art procedure for achieving this is to utilize pulverizers with different regulating devices, so as to directly produce the two desired kinds of fibers; or to couple two pulverizers in series for the production of fine fibers. However, experience has taught that such a method of making fine fibers requires the supply of a considerable power and involves the risk of the fibers being ignited.

Therefore, one has tried to work with an intermediate regulating system of the pulverizers and produce mixtures of coarse, medium, and fine fibers, and thereafter to separate the fine fibers for making the outer layers. To this effect, distributors of perforated sheet metal were utilized, or else aeromechanical selectors, but such equipment is expensive, complicated, and requires considerable power.

And lastly, the systems known so far present a considerable risk of fire and explosion.

The invention aims at counteracting the above disadvantages and, while maintaining them suspended in the air, permit the separation of two categories of fibers with a granulometric cutting limit that can be adjusted as desired, and this from either one single pulverizer or from several ones having an identical regulating device and, consequently, producing the same quality of fibers.

The invention intends also to restrict the required power and to reduce the fire and explosion hazards.

Moreover, the invention has in view to effect the pneumatic conveyance of the fibers before the separation with an economical relationship air weight/fiber weight, independent of the one required by the dispersion device and, at the same time, reducing the risk of accidents during the pneumatic conveyance.

Finally, the invention permits to utilize a combination of two selector apparatus for eventually getting three fiber qualities as, for instance, fine fibers for the outer layers, coarse fibers for the inner layer, and superfine fibers suitable for covering at least one of the two exterior layers; thus a very smooth surface is obtainable, giving the board a pleasing look and permitting the application to it special finishes without any particularly complicated preliminary treatments.

According to a first embodiment of the invention, an air current, with fibers of various dimensions suspended in it, is carried into the centrifugal separator, from which a flow of coarse fibers and a flow of fine fibers are received separately, and each of these currents is conveyed to the suction of an individual fan where it is supplemented with a certain quantity of adjustable air, in such a way that the fan sends to the forming wire an air current carrying fibers of the desired dimension and with a weight relationship of the air and the fibers representing the optimum for depositing the fibers onto the carpet.

It is clear that by proceeding in this manner, coarse fibers alternating with finer fibers can be deposited on the carpet without the necessity of using pulverizers with different regulating devices, and without encountering the other disadvantages mentioned above.

According to the invention it is also possible to send into a second separator the air current originating in the first separator and carrying the finer fibers, and then to subdivide these finer fibers into fine fibers proper and superfine fibers which will be deposited on the upper face of the mattress, before the latter leaves the apparatus where it was produced. Moreover, several separator devices can be combined so that, firstly, a layer of fine fibers destined to make up one of the outer surfaces of the board will be deposited on the forming carpet; thereafter, one or several layers of coarse fibers to constitute the core, then a layer of fine fibers and, finally, a last layer of superfine fibers, suitable to complete the other exterior surface of the board.

Further, the invention includes a particular type of centrifugal separator, especially adapted for carrying out the abovedescribed procedure.

The attached drawing, given by way of an example, will permit a better understanding of the invention, its inherent characteristics, and the advantages it offers.

FIG. 1 is a schematic vertical section of a machine proposed by the invention.

FIG. 2 is a cross section of the novel centrifugal separator.

FIG. 3 is a vertical section according to III-III (FIG. 2).

FIG. 4 is the section of one blade (vane) of the separator of FIG. 3.

FIG. 5 is a detail section along the axis of one blade.

FIG. 6 is an end view, corresponding to FIG. 5.

FIG. 7 is a section of a device of calibrated orifice.

FIG. 8 is the scheme of another embodiment of the machine according to the invention.

FIG. 9 is a section of the corresponding mattress.

In the equipment represented by FIG. 1 the fibers, suspended in an air current, arrive through pipe 1, which opens into a centrifugal separator. The latter, details of which will be given further on, has a tangential pipe 3 through which the coarser fibers pass, and a central pipe 4 which receives the finer fibers. On each of these two pipes an adjusting device 5 is interposed, a description of which will be given in what follows. Both pipes, 3 and 4, lead to the suction of a separate fan, 6 and 7 respectively. An additional air entry is also linked up with this suction, 8 and 9 respectively, each adjustable by a blade, (not shown). The back-flow of each ventilator, 6 and 7, is joined to a vertical diffuser, l2 and 13 respectively, which opens into a distribution compartment, 14 and 15 respectively. The two compartments, 14 and 15, are disposed one following the other above the horizontal upper surface of a forming wire 16, arranged and fixed in the usual manner in the form of a wire guaze. This wire circulates on the perforated casing 17a, respectively 18 a, of two suction boxes below, 17 and 18, associated with the two respective compartments l4 and 15. Each of these boxes is joined by a pipe, 19 and 20, to a separate suction fan, 21 and 22 respectively.

The functioning is as follows:

Pipe 1 is actually joined through a drier and a pneumatic conveyor to the exit opening of a pulverizer dispensing fibers of a medium and very varied granulometry, i.e., it produces a mixture of coarse, medium, and fine fibers. The forcing of the mixture into pipe 1 is effected by an air current that can be adjusted at will in order to obtain an optimal conveyance effect (i.e., with a relatively weak air weight).

The separator 2 divides the mixture, so that the coarse fibers come out of pipe 3 and the fine ones of pipe 4. The fibers, having been separated and still carried by the air current, arrive at therespective ventilators 6 and 7; these send them into compartments 14 and 15, after adding to the conveyance air current coming from pipe 1 a supplementary fraction of the surrounding air, which can be adjusted at will by blades (not shown). Thus one can create optimal conditions for disposing on the carpet 16 a lower layer A of coarse fibers, superposed by an upper layer B of fine fibers.

The compound mattress made in this manner can then be subjected to the action of the usual heating plates which compress it in order to polymerize the resin applied preliminarily to impregnate the fibers.

FIG. 2 and 3 show a preferred form of separator construction of a second type. It consists of a spiral-shaped outer shell 23 made of any appropriate material and two tangential pipes, namely a first one 23a, of a larger diameter and corresponding to the opening of pipe 1, and a second one 23b, of a smaller diameter and destined to be connected with pipe 3. The outer shell 23 has moreover a central orifice or pipe 23c to which pipe 4 of FIG. 1 is joined. Orifice 23c is surrounded by a crown of adjustable vanes (blades) 24 arranged on a circular arch of somewhat less than 180 between the inner faces of pipes 23a and 23b (i.e., their faces nearest the center). These vanes, profiles of which are represented in FIG. 4, are mounted on individual axes 25 (FIGS. 4 to 6) rotating in bearings 26 that are attached to the walls of the outer shell 23; one end of every one of the mentioned axes is provided with a regulating arm 27 that can be blocked in position on an incurved clamp mounted on the outer shell. In the shown example the clamp 28 is provided with a circular-arch aperture 28a, into which a pin 29 can be introduced, which also passes through the arm 27.

In the interior of the separator 2 the air and fiber mixture revolves counterclockwise, as indicated by the arrow. With a disposition of the vanes 24 as shown on FIG. 2, a fraction of this air passes the crown of vanes somewhat forward of the entry of tube (pipe) 23b (arrow a), whereas another fraction of the air within the crown is sucked by vortex effect between the vanes situated nearest pipe 23a (arrow b). The air current of arrows a carries the finest and a little fraction of coarser fibers along with it. In the vicinity of the central pipe 23c a certain part of the fibers does not enter this pipe, but under the effect of the centrifugal force acting against the depression, it escapes and follows the air current indicated by arrows b, thus being recycled in the direction of the spiral periphery. Owing to this recycling the separation of fibers is achieved under more favorable conditions than in the equipment known so far.

The regulating of the granulometric cutting can be done by adjusting the orientation of the vanes 24 or acting on the relative depressions at pipes 23b and 230 respectively (ventilators 6 and 7 of FIG. 1 and regulating devices or by both procedures simultaneously.

FIG. 7 shows the detail of a regulating device 5. The latter is shaped as a double cone, and its diameter at the neck is appropriately calibrated. Such a double cone plays the same role as a calibrated orifice proper, but it has the enormous advantage of not provoking eddy-currents that give rise to inopportune (ill-timed) fiber deposits. By making it easily interchangeable, the depressions in pipes 3 and 4 can be adjusted at will.

FIG. 8 shows another form of constructing a machine in accordance with the invention. The represented equipment consists of an initial portion practically identical with the one described in regard to FIG. I. Here we have again pipe 1,

selector 2, pipes 3 and 4, ventilators 6 and 7, diffusers 12 and 13, compartments 14 and 15, as well as suction boxes 17 and 18. But superposed to this first portion a second one is proposed, consisting of a pipe 30 carrying a mixture of fibers, a first separator 31, similar to separator 2; this separator 31 has also an opening 32 for coarse fibers and an opening 33 for fines fibers. Pipe 32 leads directly to the opening of a ventilator 34, joined to a diffuser 35; the latter is associated with a distributing compartment 36 and a suction caisson 37 placed right next after caisson 18. On the other hand, pipe 33 carrying fine fibers is linked up with a second centrifugal separator 38 of the same construction as separator 31. The tangential exit of this separator 38 is connected by tube (pipe) 39 to a ventilator 40; associated with the latter are: a diffuser 41, a distributing compartment 42, and a suction caisson 43, placed right next to caisson 37. In an equal manner, the central exit of separator 38 is connected by pipe 44 with a ventilator 45 to which correspond: a diffuser .46, a distributing compartment 47, and a suction box 48, disposed down from caisson 43.

It can be easily. understood that the first distribution compartment 14 provides wire 16 with a layer of fine fibers C (FIG. 9). In compartment 15 a first layer D of coarse fibers is superposed on this lowest layer. In compartment 36 this first lag 2r of coarse fibers receives another one E of identical fi rs. The mattress made thus far recerves an upper layer F of relatively fine fibers in compartment 42, and finally, in compartment 47 a final layer of superfine fibers G is added. In this manner one can obtain a board that looks particularly smooth and carefully done.

What is claimed is:

l. A centrifugal separator for separating relatively course fibers from relatively fine fibers comprising a spiral-shaped body, said body being provided with a tangentially disposed inlet passage for the entry of an air current carrying fibers for separation and a tangentially disposed outlet passage on the opposite side of said body from said inlet passage, a plurality of movable vanes disposed in a semi-circular arrangement within said body, extending between said inlet and outlet passages and separating the interior of said body into an outer spiral passage and an inner circular passage, a central outlet passage communicating with said inner passage and disposed perpendicular to the plane of said inlet and outlet passages, and means for independently adjusting each vane to provide an air current path for recycling certain fibers from said outer passage to said inner passage and back to said outer passage.

2. A centrifugal separator as set forth in claim 1 wherein the vanes adjacent said inlet passage are inclined outwardly into said outer passage and the vanes adjacent said outlet passage are inclined inwardly into said inner passage. 

1. A centrifugal separator for separating relatively course fibers from relatively fine fibers comprising a spiral-shaped body, said body being provided with a tangentially disposed inlet passage for the entry of an air current carrying fibers for separation and a tangentially disposed outlet passage on the opposite side of said body from said inlet passage, a plurality of movable vanes disposed in a semi-circular arrangement within said body, extending between said inlet and outlet passages and separating the interior of said body into an outer spiral passage and an inner circular passage, a central outlet passage communicating with said inner passage and disposed perpendicular to the plane of said inlet and outlet passages, and means for independently adjusting each vane to provide an air current path for recycling certain fibers from said outer passage to said inner passage and back to said outer passage.
 2. A centrifugal separator as set forth in claim 1 wherein the vanes adjacent said inlet passage are inclined outwardly into said outer passage and the vanes adjacent said outlet passage are inclined inwardly into said inner passage. 